1. Field of the Invention
The present invention relates to a closed-type scroll compressor. The present specification is based on Japanese Patent Application No. Hei 9-363835, the contents of which are herein incorporated in part by reference.
2. Background Art
One example of a conventional closed-type scroll compressor is shown in FIG. 5.
The inside of a closed-type housing 8 is partitioned into a high-pressure chamber 44 and a low-pressure chamber 45 by a discharge cover 31.
A scroll-type compression mechanism C is arranged in the upper part of the low-pressure chamber 45 and a motor M is arranged below it for driving it through a rotating shaft 5.
An oil reservoir 81 is formed in the bottom part of the low-pressure chamber 45.
The motor M is made up of a rotor Ma and a stator Mb, the rotor Ma is fixed to the rotating shaft 5, and the stator Mb is fixed by pressing into the closed housing 8.
The scroll-type compression mechanism C is provided with a fixed scroll 1, a swirling scroll 2, a frame 6, a rotation stopping mechanism 3, a drive bush 54, a swirling bearing 73, etc.
The fixed scroll 1 is provided with an end plate 11 and a spiral wrap 12 vertically projecting therein, and a discharge port 13 is formed in the center part of the end plate 11.
The swirling scroll 2 is provided with an end plate 21 and a spiral wrap 22 vertically projecting therein, and a drive bush 54 is inserted rotatably into a vertical boss 23 at the center of the outer surface of the end plate 21 through the swirling bearing 73.
An eccentric pin 53 projecting from the upper end of the rotating shaft 5 is rotatably inserted in to a hole 55 formed in the drive bush 54.
The fixed scroll 1 and the swirling scroll 2 are meshed with each other eccentrically at a prescribed distance and are shifted by 180.degree. to form a plurality of closed spaces 24.
The frame 6 is fixed to the closed housing 8, and the fixed scroll 1 is fastened to the frame 6 by bolts 32.
The outer surface of the end plate 21 of the swirling scroll 2 is supported slidably on a thrust surface 65 formed on the upper surface of the frame 6, and the thrust surface 65 is formed with a plurality of oil grooves 66.
The rotation stopping mechanism 3 comprising an Oldham ring, etc. that allows the orbital rotational movement of the swirling scroll 2 but does not allow the swirling scroll 2 to spin around its own axis is disposed between the peripheral edge of the outer surface of the end plate 21 of the swirling scroll 2 and the frame 6.
A cylindrical flange 16 is projected upward at the center of the outer surface of the end plate 11 of the fixed scroll 1, and the outer circumferential surface of the flange 16 and the inner circumferential surface of the cylindrical flange 38 which is projected downward toward the undersurface of the discharge cover 31 are sealed with an O-ring 39 to form a discharge cavity 42.
The central part of the discharge cover 31 is formed with a discharge hole 46 in communication with the discharge cavity 42, and the discharge hole 46 is opened and closed by a discharge valve 47.
One end of the discharge valve 47 and one end of a valve holder 48 are fixed to the outer surface of the discharge cover 31 by a bolt 49.
The upper end part of the rotating shaft 5 is supported by an upper bearing 71 provided on the frame 6 and the lower end part is supported by a lower bearing 72 provided on a stay 18.
By driving the motor M, the swirling scroll 2 is driven through the rotating shaft 5, the eccentric pin 53, the drive bush 54, the swirling bearing 73 and the boss 23, and the swirling scroll 2 is rotated in orbit while being prevented from rotating around its own axis by the rotation stopping mechanism 3.
Then, a gas is introduced into the low-pressure chamber 45 through a suction pipe 82, is passed through a gas suction passage 67 formed in the frame 6, and is sucked through a gas suction passage 68 formed in the fixed scroll 1 and suction ports 15 into the closed spaces 24.
As the volumes of the closed spaces 24 are decreased by the orbital motion of the swirling scroll 2, the gas is compressed and then the gas reaches the central part and enters the discharge cavity 42 from the discharge port 13.
Then, the gas passes the discharge hole 46, pushes open the discharge valve 47 to go into the high-pressure chamber 44, and is discharged outside therefrom through a discharge pipe 83.
At the same time, an oil in the oil reservior 81 is pumped up by an oil feeding pump 60 disposed at the lower end part of the rotating shaft 5 and is passed through an oil feeding passage 52 formed in the rotating shaft 5 to lubricate the lower bearing 72 and the upper bearing 71. After the oil discharged from the tip of the oil feeding passage 52 lubricates the drive bush 54 and the swirling shaft 73, the oil passes a recess 61 formed in the central part of the upper surface of the frame 6 and an oil drainage passage 62 and drops through an oil passage 84 formed in the stator Mb of the motor M into the oil reservior 81.
When the above conventional closed-type scroll compressor is operated, the gas sucked through the suction pipe 82 into the low-pressure chamber 45 is stirred by the rotor Ma of the motor M. Accordingly, the oil dropping from the oil drainage passage 62 is blown off by the gas swirling in the low-pressure chamber 45 to go hardly into the oil passage 84 and accompanies this gas, thereby, the oil is sucked by the scroll-type commpression mechanism C.
As a result, since the amount of the oil dropping in to the oil reservior decreases and the amount of the oil raised, that is, the amount of the oil that accompanies the discharge gas and which is discharged from the closed housing 8, is increased, the amount of the oil in the oil reservoir 81 decreases, leading to concern that an accident, such as defective lubrication and seizing due to the defective lubrication, will occur. To counter this, it is conceivable to provide an oil drainage passage in communication with the above recess 61 or the oil drainage passage 62 and separated from the low-pressure chamber 45, but it makes the structure in the closed-type scroll compressor complicated.